The addition of anti-lock circuits to brake systems introduced a need to maintain a substantially constant quantity of fluid in a system even though when the anti-lock circuit functions in a build and decay function. The introduction of accumulators and/or pumps as disclosed in U.S. Pat. Nos. 4,598,955, 4,944,565 and 5,120,115 to the brake system which are controlled by various solenoid valves provide supplementary fluid during an anti-lock function have proven acceptable for most brake systems. To improve the operation and control of a vehicle, an anti-spin function has been added which utilizes some of the same components of an anti-lock system to limit the rotation differential between drive wheels of a vehicle. In such anti-spin systems, a pump supplies a controller with pressurized fluid which is selectively supplied to effect braking of the faster rotating drive wheel and bring it into synchronization with another drive wheel. The pump draws fluid from the master cylinder reservoir through the compensation port associated with a pressurizing chamber. Under some circumstances, the size of the compensation port could restrict the development of pressurized fluid to effect the anti-spin function effectively and when center port compensation occurs, the flow of fluid through the compensation port could reduce the effective functional life cycle of the components.